At 22-24 h after unilateral ganglionectomy (SX), intraocular pressure (IOP) was significantly (p < 0.001) reduced in SX eyes compared either with the contralateral, normally innervated eyes or with baseline measurements. SX raised prostaglandin E2 (PGE2), PGF2alpha, and neuropeptide Y (NPY) concentrations in the aqueous humor but reduced these levels in the iris-ciliary body. At 22-24 h after bilateral SX, flurbiprofen (0.03%) significantly (p < 0.001) inhibited the reduction of IOP and the elevation of PGE2 and PGF2alpha levels in the aqueous humor. We conclude that PGs mediate the reduction of IOP at 22-24 h after SX.